Principle Of Operation; Adjustment - Siemens SITRANS LVL200E Operating Instructions Manual

Application area
Functional principle
Voltage supply
MAN-100411
3.2

Principle of operation

SITRANS LVL200E is a point level sensor with tuning fork for point
level detection.
It is designed for industrial use in all areas of process technology and
can be used in liquids.
Typical applications are overfill and dry run protection. The small
tuning fork allows use in all kinds of tanks and vessels. Thanks to its
simple and rugged measuring system, SITRANS LVL200E is virtually
unaffected by the chemical and physical properties of the liquid.
It functions even under difficult conditions such as turbulence, air bub-
bles, foam generation, buildup, strong external vibration or changing
products.
Function monitoring
The electronics module of SITRANS LVL200E continuously monitors
the following criteria via frequency evaluation:
•
Strong corrosion or damage on the tuning fork
•
Loss of vibration
•
Line break to the piezo drive
If one of these faults is detected, the electronics signals it via a
defined current to the signal conditioning instrument. The connection
cable to the sensor is also monitored for line break and short-circuit.
The tuning fork is piezoelectrically energised and vibrates at its
mechanical resonance frequency of approx. 1200 Hz. The piezos are
fixed mechanically and are hence not subject to temperature shock
limitations. The frequency changes when the tuning fork is covered
by the medium. This change is detected by the integrated electronics
module, transferred as a current value to the processing system and
converted there into a switching command.
Depending on your requirements, SITRANS LVL200E with two-
wire electronics can be connected to different signal conditioning
instruments. Compatible signal conditioning instruments are listed in
chapter "Technical data".
The data for power supply are specified in chapter "Technical data".
3.3

Adjustment

The switching condition of SITRANS LVL200E with plastic housing
can be checked when the housing is closed (signal lamp). With the
basic setting, products with a density ≥ 0.7 g/cm³ (0.025 lbs/in³) can
be detected. The instrument can be adapted if products with lower
density are to be measured.
On the electronics module you will find the following display and
adjustment elements:
•
Signal lamp for indication of the switching condition (green/red)
•
DIL switch for adaptation to the product density
SITRANS LVL200E - Operating Instructions
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